2,762 research outputs found
Lyapunov vs. Geometrical Stability Analysis of the Kepler and the Restricted Three Body Problem
In this letter we show that although the application of standard Lyapunov
analysis predicts that completely integrable Kepler motion is unstable, the
geometrical analysis of Horwitz et al [1] predicts the observed stability. This
seems to us to provide evidence for both the incompleteness of the standard
Lyapunov analysis and the strength of the geometrical analysis. Moreover, we
apply this approach to the three body problem in which the third body is
restricted to move on a circle of large radius which induces an adiabatic time
dependent potential on the second body. This causes the second body to move in
a very interesting and intricate but periodic trajectory; however, the standard
Lyapunov analysis, as well as methods based on the parametric variation of
curvature associated with the Jacobi metric, incorrectly predict chaotic
behavior. The geometric approach predicts the correct stable motion in this
case as well.Comment: 9 pages, 14 figure
SUSY transformation of the Green function and a trace formula
An integral relation is established between the Green functions corresponding
to two Hamiltonians which are supersymmetric (SUSY) partners and in general may
possess both discrete and continuous spectra. It is shown that when the
continuous spectrum is present the trace of the difference of the Green
functions for SUSY partners is a finite quantity which may or may not be equal
to zero despite the divergence of the traces of each Green function. Our
findings are illustrated by using the free particle example considered both on
the whole real line and on a half line
Discrimination of the Healthy and Sick Cardiac Autonomic Nervous System by a New Wavelet Analysis of Heartbeat Intervals
We demonstrate that it is possible to distinguish with a complete certainty
between healthy subjects and patients with various dysfunctions of the cardiac
nervous system by way of multiresolutional wavelet transform of RR intervals.
We repeated the study of Thurner et al on different ensemble of subjects. We
show that reconstructed series using a filter which discards wavelet
coefficients related with higher scales enables one to classify individuals for
which the method otherwise is inconclusive. We suggest a delimiting diagnostic
value of the standard deviation of the filtered, reconstructed RR interval time
series in the range of (for the above mentioned filter), below
which individuals are at risk.Comment: 5 latex pages (including 6 figures). Accepted in Fractal
A new HW Vir binary from the Palomar Transient Factory: PTF1 J072455.75+125300.3 - An eclipsing subdwarf B binary with a M-star companion
We report the discovery of an eclipsing binary -- PTF1 J072456125301--
composed of a subdwarf B (sdB) star () with a faint companion.
Subdwarf B stars are core helium-burning stars, which can be found on the
extreme horizontal branch. About half of them reside in close binary systems,
but few are known to be eclipsing, for which fundamental stellar parameters can
be derived.\newline We conducted an analysis of photometric data and spectra
from the Palomar 60'' and the 200" Hale telescope respectively. A quantitative
spectral analysis found an effective temperature of
\,K, log g = and
log(, typical for an sdB star. The
companion does not contribute to the optical light of the system, except
through a distinct reflection effect. From the light curve an orbital period of
0.09980(25)\,d and a system inclination of 83.56\pm0.30\,^{\circ} were
derived. The radial velocity curve yielded an orbital semi-amplitude of
K_1=95.8\pm 8.1\,\text{km s^{-1}}. The mass for the M-type dwarf companion
is . PTF1\,J072456125301 has similar atmospheric
parameters to those of pulsating sdB stars (V346 Hya stars). Therefore it could
be a high-priority object for asteroseismology, if pulsations were detected
such as in the enigmatic case of NY Vir.Comment: Accepted to A&A, 7pages, 4 figure
Changes at Work
Assesses the changing nature of work, the meaning of work, dissatisfaction with work, and interest in work reform.https://research.upjohn.org/up_press/1137/thumbnail.jp
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